Mercedes' hand hidden as Vettel tops FP3

Sebastian Vettel set the fastest time of FP3 as Mercedes didn't show its true pace in qualifying trim in Korea.

Friday's pace-setter Lewis Hamilton was quickest on the medium tyre with just 20 minutes of the session remaining, but Vettel found over a second when switching to the supersofts and neither Mercedes driver was able to match his time, with the whole 0.4s deficit coming in the first sector and Hamilton twice caught in traffic.

Mark Webber was only 0.137s off his team-mate in second place but won't be a threat on the grid with a 10-place grid penalty hanging over him. Behind the two Red Bulls and Mercedes it was Fernando Alonso, who ended the session 0.6s off Vettel's pace, though he should have been more closely challenge by Romain Grosjean who lost time on his flying lap with an error in the final sector.

Grosjean does appear to have the edge over team-mate Kimi Raikkonen again, with Raikkonen appearing to struggle with the handling of his Lotus on his wat to the eighth quickest time of the session. Despite optimism from Jenson Button on Friday evening, McLaren still appears to be lacking the pace to challenge Lotus.

One slight concern for Hamilton was his brakes as he complained of vibrations on his installation lap at the start of the session and was confined to the garage for a short period while Mercedes changed the brake material.

Jules Bianchi had a spin early on, losing the rear entering Turn 9 having had one hand off the steering wheel, but with grip levels improving there were less off-track excursions than on Friday.

The International Rugby Board (IRB) have stripped Australia of the right to host a round of the World Sevens Series, scheduled for Brisbane on 16-17 February, after the Australian government's refusal to provide visas for the squad from Fiji